Various systems for reinforcing building structural components for making reinforced concrete structures have been proposed. Generally, steel reinforcing unit is embedded in the cast concrete for providing the concrete structure to improve tensile strength, compressive strength and shear capacity. Specifically, such systems include one or more stirrups or ties with a series of bars placed along the axis of the member to form a cage like apparatus. Such stirrups and ties constitute one of the most critical factors of quality and seismic resistance of buildings. Some of such existing stirrups/tie for reinforcing the building structural components are described herein.
As per the prior arts described herein, FIG. 1 (PRIOR ART) describes a concrete structure 10 in which conventional ties 2 are installed on the vertical bars 4 and convention stirrups 6 are installed on the horizontal bars 8.
FIG. 2 (PRIOR ART) describes a conventional rectangular tie 20 (similar to conventional ties 2 or conventional stirrups bused in constructing a concrete structure (for example, the concrete structure 10). Tie 20 is usually made of solid steel bars of circular cross section with a diameter ‘db’, length breadth ‘B’ and major diagonal dimension ‘D’. Further, tie 20 comprises hooks 22 for anchoring the ties 20 to the load bearing element of the structure (for structures such as bars 8 of FIG. 1). Such conventional ties 20 when disposed around the plurality of the vertical bars/horizontal bars form a cage like structure.
FIG. 3 (PRIOR ART) illustrates such cage like structure 30 wherein a plurality of conventional rectangular ties 20 is disposed around the vertical bars 32. Specifically, the conventional rectangular ties 20 are placed one above the other parallel to the surface on which the vertical bars 32 are placed and perpendicular to the vertical bars 32. Two rectangular ties 20 have a height difference (spacing) of ‘h’ between them.
Similarly, FIG. 4 (PRIOR ART) describes a conventional circular tie 40 (similar to conventional ties 2 or conventional stirrups 6) used in constructing a concrete structure (for example, the concrete structure 10). Tie 40 is usually made of solid steel bars of circular cross section having a diameter ‘db’, and cage diameter ‘D’. Further, tie 40 comprises hooks 42 for anchoring the ties 40 to the load bearing element of the structure. Such conventional ties 40 when disposed around the plurality of the vertical bars/horizontal bars form a cage like structure.
FIG. 5 (PRIOR ART) illustrates such cage like structure 50 wherein a plurality of conventional circular ties 40 is disposed around the vertical bars 52. Specifically, the conventional circular ties 40 are placed one above the other parallel to the surface on which the vertical bars 52 are placed and perpendicular to the vertical bars 52. Two circular ties 40 have a height difference (spacing) of ‘h’ between them.
As illustrated in FIG. 1 (PRIOR ART), FIG. 3 (PRIOR ART) and FIG. 5 (PRIOR ART) the conventional configuration of the ties/stirrups only improves confinement of concrete at location of the ties/stirrups where it is disposed. Specifically, confinement received by concrete is localized and dependent on the spacing of the ties/stirrups. Improvement in such concrete confinement is achieved on reducing the spacing of ties/stirrups which results in heavy congestion and consumption of reinforcement steel.
Further, when subjected to an earthquake, requirement of steel reinforcement in the form of ties/stirrups increases to meet the additional demand. Conventional configuration of the ties/stirrups as illustrated in FIG. 1 (PRIOR ART), FIG. 3 (PRIOR ART) and FIG. 5 (PRIOR ART) is localized and confined to its own plane. In this case, resistance to opening of cracks provided by steel reinforcement is limited to the plane where the tie/stirrups are confined. This leads to strength degradation for cycle after cycle of the earthquake ground motion (vibration) or under impact loads. Likewise, when structural elements are subject to impact loads (such as blast), conventional tie pattern systems are not efficient to resist such loads.
Accordingly, there exists a need for a lateral reinforcement system that provides enhanced performance of concrete structures compared to the conventional patterns. Also, there exists a need of a lateral reinforcement system which utilizes less amount of steel, having improved constructability, possessing an enhanced load carrying capacity, having an enhanced earthquake resistance and energy absorption and is cost effective.